Abstract: In order to clarify the inhibiting effect of kelp on the activity of angiotensin converting enzyme, the effects of different additive amount of cellulase and enzymolysis time on the inhibition of angiotensin converting enzyme activity by kelp pulp were investigated by the single factor experiment and response surface optimization test. The results showed that the enzymatic hydrolysis of kelp pulp with cellulase was carried out, and the mathematical model of the inhibition rate Y of ACE activity in kelp enzymatic hydrolysate, the enzyme additive amount X₁ and the enzymolysis time X₂ was established:Y=-114.273 04+0.005 72X₁+1.491 99X₂-3.333 33×10^-7X₁X₂-2.552 00×10^-7X₁²-0.004 47X₂². The optimal enzymolysis condition was obtained as follows:after the kelp was cut and homogenized, 11 060 U·g^-1 cellulase was added at pH 6.0 and the enzymatic hydrolysis was performed at room temperature for 169 min. The inhibition rate of the obtained enzymatic hydrolysate on ACE activity was about 41.43%. The results showed that the enzyme hydrolysate of kelp had a high inhibitory effect on the activity of angiotensin converting enzyme.